The present invention relates to a permanent magnet type AC synchronous motor including a linear and a rotary motor, wherein initial magnetic poles of the AC synchronous motor are estimated without using a magnetic pole sensor (pole sensor).
Information on an initial magnetic pole position detected from a magnetic pole sensor is required when an AC synchronous motor is started, such that the AC synchronous motor operates in accordance with commands based on correct information on a detected initial magnetic pole position. There may arise such problems as when the information on the detected initial magnetic pole position shifts from the magnetic pole position of the AC synchronous motor by xc2x190 degrees, no torque is generated so that the AC synchronous motor does not operate, and when the shift exceeds xc2x190 degrees, the AC synchronous motor reversely rotates as opposed to a command. From such reasons, the correct information on a detected initial magnetic pole position is critical in the AC synchronous motor, so that a variety of initial magnetic pole estimating methods have been devised for AC synchronous motor in order to acquire correct information on a detected initial magnetic pole position. A relationship between an offset angle of an initial magnetic pole position and a generated torque (hereinafter, a thrust force of a linear motor is also shown as a torque) is represented by Equation (1) and shown in FIG. 16.
T=Tmxc3x97cos(xcex8error)xe2x80x83xe2x80x83(1)
where T is a generated torque, Tm is a maximum value of the torque, and xcex8error is an offset angle of the initial magnetic pole position.
A prior art technique described in Japanese Patent Laid-Open No. 153576/1994 applies a voltage corresponding to an arbitrary initial magnetic pole position angle to estimate the initial magnetic pole position from information on a rotating direction and a rotational speed of a motor at that time. This initial magnetic pole estimating method repeats the estimation to find a correct initial magnetic pole position.
However, the prior art technique involves a repetition-based trial and error method which approaches from a wide estimation error range to a narrower estimation error range of the initial magnetic pole position to estimate a true value for the initial magnetic pole position of an AC synchronous motor, and experiences the following problems:
(1) a correct initial magnetic pole position cannot be estimated (a magnetic pole position estimation accuracy range is within xc2x130xc2x0);
(2) a motor operation range can become wider during an estimation of an initial magnetic pole position;
(3) an estimation time can be long; and
(4) an application to a load is difficult if disturbance such as a large static friction, cogging and the like exists in the load.
To solve the foregoing problems, it is an object of the present invention to make full use of the performance and characteristics of an AC synchronous motor by:
(1) the ability to estimate a magnetic pole position in a short time;
(2) the ability to freely set a range in which the motor can operate;
(3) the ability to minimize a range in which the motor can operate;
(4) the applicability to a load even if disturbance or large cogging torque exists in the load; and
(5) the ability to correctly estimate a true value for an initial magnetic pole position.
The gist of an initial magnetic pole estimating apparatus for an AC synchronous motor according to the present invention lies in the following (1)-(32).
(1) An initial magnetic pole estimating apparatus for an AC synchronous motor, equipped in an AC synchronous motor controller comprising speed control means for calculating a command torque (command current) from a command speed, current control means for driving the AC synchronous motor in accordance with the command torque (command current), and a PWM power converter, wherein the initial magnetic pole estimating apparatus is characterized by having speed deviation calculating means for subtracting the detected speed from the command speed generated by command speed pattern generating means to calculate a speed deviation, a speed gain control unit for multiplying the speed deviation by a speed gain to calculate a command torque (command current), mode section determining means for determining a mode section (a first cyclic section and a second cyclic section) from the command speed, a mode switch for switching a mode section to any of the first cyclic section and the second cyclic section in accordance with a result in the mode section determining means, data acquisition speed section determining means for determining whether the command speed is in a data acquisition speed section when the first cyclic section is selected, a first command torque calculating means (first command current calculating means) for calculating first command torque data (first command current data) from the command torque (the command current) in the determined data acquisition speed section, data acquisition speed section determining means for determining whether the command speed is in the data acquisition speed section when the second cyclic section is selected, second command torque calculating means (second command current calculating means) for calculating second command torque data (second command current data) from the command torque (the command current) in the determined data acquisition speed section, and estimated initial magnetic pole calculating means for calculating an estimated initial magnetic pole position using information on the first command torque data (the first command current data) and the second command torque data (the second command current data).
(2) An initial magnetic pole estimating apparatus for an AC synchronous motor equipped in an AC synchronous motor controller comprising PWM power converting means for converting a direct current voltage to an arbitrary alternate current voltage to drive the AC synchronous motor, three-phase current detecting means for detecting a three-phase current of the AC synchronous motor, an electric angle detecting means for detecting a relative electric angle of the AC synchronous motor, three-phase/two-phase coordinate conversion calculating means for performing a three-phase/two-phase coordinate conversion from a detected three-phase current to a detected two-phase current using the detected electric angle, detected speed calculating means for calculating a detected speed from the detected electric angle, two-phase current error calculating means for subtracting the detected two-phase current from a two-phase command current comprised of a q-axis command current and a d-axis command current to calculate a current error, a two-phase current proportion integration control unit for multiplying the current error by a two-phase current proportion integration gain to calculate a two-phase command voltage, two-phase/three-phase coordinate conversion calculating means for performing a two-phase/three-phase coordinate conversion from the two-phase command voltage to a three-phase command voltage using the detected electric angle, and PWM gate pulse calculating means for comparing the three-phase command voltage with a carrier waver to calculate a PWM gate pulse and outputting the PWM gate pulse to the PWM power converting means, wherein the initial magnetic pole estimating apparatus for an AC synchronous motor is characterized by having default initial magnetic pole setting means for setting a default initial magnetic pole position to zero, command speed pattern generating means for generating a command speed as a two-cycle waveform, speed deviation calculating means for subtracting the detected speed from the command speed to calculate a speed deviation, a speed gain control unit for multiplying the speed deviation by a speed gain to calculate a command torque (command current), mode section determining means for determining a mode section (a first cyclic section and a second cyclic section) from the command speed, a mode switch for switching a mode section to any of the first cyclic section and the second cyclic section in accordance with a result in the mode section determining means, acceleration section determining means for inputting the command torque (the command current) to the q-axis command current and inputting zero to the d-axis command current, when the first cyclic section is selected, and determining whether or not the command speed is in a positive acceleration section, first command torque calculating means (first command current calculating means) for calculating first maximum command torque data (first maximum command current data) from the command torque which is the determined positive acceleration section, first memory storing means for storing the first maximum command torque in a memory, acceleration section determining means for inputting zero to the q-axis command current and inputting the command torque (the command current) to the d-axis command current when the second cyclic section is selected, and determining whether or not the command speed is in a positive acceleration section, second command torque calculating means (second command current calculating means) for calculating second maximum command torque data (second maximum command current data) from the command torque which is in the determined positive acceleration section, second memory storing means for storing the second maximum command torque in a memory, estimated initial magnetic pole calculating means for calling the maximum command torques (first and second maximum command torques) from the memories after the command speed has terminated a second cycle to calculate an estimated initial magnetic pole position using the information, and compensated initial magnetic pole calculating means for adding the estimated initial magnetic pole position to the default initial magnetic pole position to calculate a compensated initial magnetic pole position.
(3) An initial magnetic pole estimating apparatus for an AC synchronous motor equipped in an AC synchronous motor controller comprising PWM power converting means for converting a direct current voltage to an arbitrary alternate current voltage to drive the AC synchronous motor, three-phase current detecting means for detecting a three-phase current of the AC synchronous motor, an electric angle detecting means for detecting a relative electric angle of the AC synchronous motor, detected speed calculating means for calculating a detected speed from the detected electric angle, three-phase command current calculating means for calculating three-phase command current comprised of a A-phase command current, a B-phase command current and a C-phase command current from a command torque (command current) using the detected electric angle, three-phase current error calculating means for subtracting the detected three-phase current from a three-phase command current to calculate a current error, a three-phase current proportion integration control unit for multiplying the current error by a three-phase current proportion integration gain to calculate a three-phase command voltage, and PWM gate pulse calculating means for comparing the three-phase command voltage with a carrier waver to calculate a PWM gate pulse and outputting the PWM gate pulse to the PWM power converting means, wherein the initial magnetic pole estimating apparatus for an AC synchronous motor is characterized by having default initial magnetic pole setting means for setting a default initial magnetic pole position to zero, command speed pattern generating means for generating a command speed as a two-cycle waveform, speed deviation calculating means for subtracting the detected speed from the command speed to calculate a speed deviation, a speed gain control unit for multiplying the speed deviation by a speed gain to calculate a command torque (command current), mode section determining means for determining a mode section (a first cyclic section and a second cyclic section) from the command speed, a mode switch for switching a mode section to any of the first cyclic section and the second cyclic section in accordance with a result in the mode section determining means, three-phase command current converting means operative when the first cyclic section is selected for adding a shift angle equal to zero degrees to the detected electric angle (without phase change), and calculating the three-phase command current from the command torque (the command current), acceleration section determining means for determining whether or not the command current is in a positive acceleration section, first command torque calculating means (first command current calculating means) for calculating a value of a first maximum command torque (first maximum command current) from the command torque which is in the determined positive acceleration section, first memory storing means for storing the first maximum command torque in a memory, the three-phase command current converting means operative when the second cyclic section is selected for adding a shift angle equal to 90 degrees to the detected electric angle (a phase change by 90 degrees), and thereafter calculating the three-phase command current from the command torque (the command current), acceleration section determining means for determining whether or not the command speed is in a positive acceleration section, second command torque calculating means (second command current calculating means) for calculating a value of a second maximum command torque (second maximum command current) from the command torque which is in the determined positive acceleration section, second memory storing means for storing the second maximum command torque in a memory, estimated initial magnetic pole calculating means for calling the maximum command torques (first and second maximum command torques) from the memories after the command speed has terminated a second cycle to calculate an estimated initial magnetic pole position using the information, and compensated initial magnetic pole calculating means for adding the estimated initial magnetic pole position to the default initial magnetic pole position to calculate a compensated initial magnetic pole position.
(4) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(3), characterized in that the command speed pattern generating means is capable of arbitrarily setting an acceleration/deceleration section time and a constant speed section time, arbitrarily setting a speed waveform in the acceleration/deceleration section, and arbitrarily setting an amplitude value for a command speed to generate the command speed as a trapezoidal wave, a triangular waver, a rectangular wave, a zero-speed wave, a sinusoidal wave, and the like as a two-cycle waveform.
(5) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(4), characterized in that the speed gain control unit functions as a speed proportion control unit, a speed proportion integration control unit or a speed integration control unit in a combination of a speed proportion control unit and a speed integration control unit.
(6) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(5), characterized in that the current control means is a dq current control means (vector current control means), or three-phase current control means.
(7) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(6), characterized in that in the dq current control means used as the current control means, the command current is inputted to the q-axis command current, and a constant value is inputted to the d-axis command current in the first cyclic section, and the command current is inputted to the d-axis command current, and a constant value is inputted to the q-axis command current in the second cyclic section.
(8) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(7), characterized in that the constant value is an arbitrary number.
(9) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(8), characterized in that in the three-phase current control means used as the current control means, in the first cyclic section, after a shift angle equal to zero degrees is added to the detected electric angle (without phase change), the command torque (the command current) is converted to a three-phase command current as shown in the following equations, and in the second cyclic section, after a shift angle equal to 90 degrees is added to the detected electric angle (phase change by 90 degrees), the command torque (the command current) is converted to a three-phase command current as shown in the following equations.
Ia*=I*xc3x97cos(xcex8fbxe2x88x92xcex8shift)
Ib*=I*xc3x97cos(xcex8fbxe2x88x92xcex8shiftxe2x88x92120 degrees)
Ic*=I*xc3x97cos(xcex8fbxe2x88x92xcex8shiftxe2x88x92240 degrees)
where I* is a command torque (command current);
xcex8fb is a detected electric angle (relative position);
xcex8shift is a shift angle (zero degrees in the first cyclic section, and 90 degrees in the second cyclic section);
Ia* is an A-phase command current;
Ib* is a B-phase command current; and
Ic* is a C-phase command current.
(10) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(9), characterized in that in the current control means, the command torque (the command current) is treated as the command current in the first cyclic section after a shift angle equal to zero degrees is added to the detected electric angle (without phase change), and the command torque (the command current) is treated as the command current in the second cyclic section after a shift angle equal to 90 degrees is added to the detected electric angle (phase change by 90 degrees).
(11) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(10), characterized in that the data acquisition speed section is comprised of a combination of a positive acceleration section, a negative acceleration section, a positive deceleration section, a negative deceleration section, a positive constant speed section, and a negative constant speed section.
(12) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(11), characterized in that the data acquisition speed section determining means is acceleration section determining means when the magnetic pole estimating data is acquired in an acceleration section; constant speed section determining means when acquired in a constant speed section; acceleration/constant speed section determining means when acquired in an acceleration section and a constant speed section; deceleration/constant speed section determining means when acquired in a deceleration section and a constant speed section; acceleration/deceleration determining means when acquired in an acceleration section and a deceleration section; and an acceleration/deceleration/constant speed section determining means when acquired in an acceleration section, a deceleration section and a constant speed section.
(13) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(12), characterized in that when the data acquisition speed section determining means is the constant speed section determining means, the magnetic pole estimating data is calculated after the arbitrary time set due to the fact that it can be set from zero to an arbitrary time (however, the arbitrary time is smaller than an end time of the constant speed section) until the end time of the constant speed section.
(14) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(13), characterized by having first memory storing means for storing the first command current data calculated in the first cyclic section in a memory, and second memory storing means for storing the second command current data calculated in the second cyclic section in a memory.
(15) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(14), characterized by calling the command torque data (first and second command torque data) from the memory.
(16) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(15), characterized in that the estimated initial magnetic pole position is calculated as expressed by tanxe2x88x921 (the first command current data/the second command current data), or a combination of cosxe2x88x921 and sinxe2x88x921, or the estimated initial magnetic pole position is calculated as expressed by xcexa3(tanxe2x88x921 (the first instantaneous command current data/the second instantaneous command current data) )/k when the first and second command current data are instantaneous command currents, or calculated from a relationship between the first command current data and the second command current data.
(17) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(16), characterized in that the first command current data and second command current data calculated by the first command current calculating means and the second command current calculating means are a maximum command current, an average command current and an instantaneous command current, wherein the maximum command current is a maximum value calculated from a command current which is in the data acquisition speed section, the average command current is an average of the command current which is in the data acquisition speed section, and the instantaneous command current is a command current which is an instantaneously calculated command current which is in the data acquisition speed section.
(18) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(17), characterized in that in the command speed, a pause section in which the command speed has a zero command speed is provided when switching between positive and negative, and a time for the pause section can be arbitrarily set.
(19) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(18), characterized in that in the command speed, a pause section in which the command speed is zero is provided between a first cyclic section in a first cycle and a second cyclic section in a second cycle, and a section is switched during the pause section.
(20) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(19), characterized in that the command current, a pause section is provided when a forced phase change is performed, and the phase change is performed in the pause section.
(21) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(20), characterized by having speed integration gain processing means for performing speed integration gain processing (clearing, holding and the like of an integration term) of the speed gain control unit, when the first cyclic section is switched to the second cyclic section, or when a forced phase change is performed, in the command current.
(22) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(21), characterized in that an axial direction determining command speed provided for determining a direction (region) of a torque axis or a magnetic flux axis of the AC synchronous motor uses a first cyclic waveform of the command speed according to the foregoing (4).
(23) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(22), characterized in that a user sets one or more of a speed deviation limit level, a torque limit level, a speed limit level, and a data deviation limit level in a parameter setting memory within the initial magnetic pole estimating apparatus for an AC synchronous motor.
(24) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(23), characterized in that excessive speed deviation determining means compares a speed deviation calculated by subtracting the detected speed from the axial direction determining command speed with the speed deviation limit level to determine an excessive speed deviation of the motor.
(25) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(24), characterized in that excessive torque determining means compares a command torque supplied from the speed control unit with the torque limit level to determine an excessive command torque for the motor.
(26) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(25), characterized in that excessive speed determining means compares the detected speed with the speed limit level to determine an excessive speed for the motor.
(27) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(26), characterized by dividing 360 degrees of electric angle by a certain positive integer n, assuming that the torque axis exists in a certain direction within 360 degrees, controlling the AC synchronous motor with an axial direction determining command speed, determining an excessive speed deviation in the excessive speed deviation determining means, and estimating a direction of the torque axis from the determination result.
(28) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(27), characterized by assuming that the torque axis of the AC synchronous motor is in another direction in accordance with the result of the excessive speed deviation determination, and estimating the direction of the torque axis of the AC synchronous motor by repeating the operation of controlling the AC synchronous motor with the axial direction determining command speed, and determining the excessive speed deviation in the excessive speed deviation determining means by a predefined subroutine.
(29) An initial magnetic pole estimating apparatus for an AC synchronous motor, characterized by estimating the direction of the torque axis of the AC synchronous motor in the axial direction determining means according to any one of the foregoing (22)-(28), and thereafter estimating an initial magnetic pole position of the AC synchronous motor in the calculation processing according to the foregoing (1), (2) or (3).
(30) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(29), characterized in that excessive data deviation determining means compares a difference between the first command torque data and the second command torque data (data difference) with the data deviation limit level to determine an excessive data deviation.
(31) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(30), characterized by determining an excessive data deviation in the excessive data deviation determining means, and estimating an initial magnetic pole position of the AC synchronous motor again by the calculation processing according to the foregoing (1), (2) or (3) after changing to a predefined phase, when the determination result shows xe2x80x9cdata deviationxe2x89xa7data deviation limit level.xe2x80x9d
(32) An initial magnetic pole estimating apparatus for an AC synchronous motor according to any one of the foregoing (1)-(31), characterized in that the AC synchronous motor is a rotary motor or a linear motor.